From 317ed150a1f47501b73fff6355244982ce0ab19e Mon Sep 17 00:00:00 2001 From: ramansahasi Date: Mon, 1 Oct 2018 07:29:53 +0530 Subject: [PATCH] BAEL-2015 Memory leaks in Java (#5295) * BAEL-2015_Memory_leaks_in_Java * Ignored tests * Update NonStaticFieldsDemo.java * Corrected class name * converted tabspaces to whitespaces --- .../memoryleaks/equalshashcode/Person.java | 9 +++++ .../equalshashcode/PersonOptimized.java | 25 ++++++++++++++ .../memoryleaks/finalize/BulkyObject.java | 32 +++++++++++++++++ .../finalize/BulkyObjectOptimized.java | 22 ++++++++++++ .../memoryleaks/innerclass/BulkyObject.java | 22 ++++++++++++ .../innerclass/InnerClassDriver.java | 17 ++++++++++ .../innerclass/InnerClassWrapper.java | 10 ++++++ .../innerclass/StaticNestedClassWrapper.java | 10 ++++++ .../internedstrings/InternedString.java | 17 ++++++++++ .../ReadStringFromFileUtil.java | 34 +++++++++++++++++++ .../internedstrings/StringObject.java | 17 ++++++++++ .../staticfields/NonStaticFieldsDemo.java | 21 ++++++++++++ .../staticfields/StaticFieldsDemo.java | 21 ++++++++++++ .../PersonMemoryLeakUnitTest.java | 33 ++++++++++++++++++ .../finalize/FinalizeMemoryLeakUnitTest.java | 28 +++++++++++++++ .../StaticInnerClassMemoryLeakUnitTest.java | 20 +++++++++++ .../StringInternMemoryLeakUnitTest.java | 20 +++++++++++ .../NonStaticFieldsMemoryLeakUnitTest.java | 26 ++++++++++++++ .../StaticFieldsMemoryLeakUnitTest.java | 26 ++++++++++++++ 19 files changed, 410 insertions(+) create mode 100755 core-java/src/main/java/com/baeldung/memoryleaks/equalshashcode/Person.java create mode 100755 core-java/src/main/java/com/baeldung/memoryleaks/equalshashcode/PersonOptimized.java create mode 100755 core-java/src/main/java/com/baeldung/memoryleaks/finalize/BulkyObject.java create mode 100644 core-java/src/main/java/com/baeldung/memoryleaks/finalize/BulkyObjectOptimized.java create mode 100755 core-java/src/main/java/com/baeldung/memoryleaks/innerclass/BulkyObject.java create mode 100755 core-java/src/main/java/com/baeldung/memoryleaks/innerclass/InnerClassDriver.java create mode 100755 core-java/src/main/java/com/baeldung/memoryleaks/innerclass/InnerClassWrapper.java create mode 100755 core-java/src/main/java/com/baeldung/memoryleaks/innerclass/StaticNestedClassWrapper.java create mode 100644 core-java/src/main/java/com/baeldung/memoryleaks/internedstrings/InternedString.java create mode 100644 core-java/src/main/java/com/baeldung/memoryleaks/internedstrings/ReadStringFromFileUtil.java create mode 100644 core-java/src/main/java/com/baeldung/memoryleaks/internedstrings/StringObject.java create mode 100644 core-java/src/main/java/com/baeldung/memoryleaks/staticfields/NonStaticFieldsDemo.java create mode 100644 core-java/src/main/java/com/baeldung/memoryleaks/staticfields/StaticFieldsDemo.java create mode 100644 core-java/src/test/java/com/baeldung/memoryleaks/equalshashcode/PersonMemoryLeakUnitTest.java create mode 100644 core-java/src/test/java/com/baeldung/memoryleaks/finalize/FinalizeMemoryLeakUnitTest.java create mode 100644 core-java/src/test/java/com/baeldung/memoryleaks/innerclass/StaticInnerClassMemoryLeakUnitTest.java create mode 100644 core-java/src/test/java/com/baeldung/memoryleaks/internedstrings/StringInternMemoryLeakUnitTest.java create mode 100644 core-java/src/test/java/com/baeldung/memoryleaks/staticfields/NonStaticFieldsMemoryLeakUnitTest.java create mode 100644 core-java/src/test/java/com/baeldung/memoryleaks/staticfields/StaticFieldsMemoryLeakUnitTest.java diff --git a/core-java/src/main/java/com/baeldung/memoryleaks/equalshashcode/Person.java b/core-java/src/main/java/com/baeldung/memoryleaks/equalshashcode/Person.java new file mode 100755 index 0000000000..e16d1ae6da --- /dev/null +++ b/core-java/src/main/java/com/baeldung/memoryleaks/equalshashcode/Person.java @@ -0,0 +1,9 @@ +package com.baeldung.memoryleaks.equalshashcode; + +public class Person { + public String name; + + public Person(String name) { + this.name = name; + } +} diff --git a/core-java/src/main/java/com/baeldung/memoryleaks/equalshashcode/PersonOptimized.java b/core-java/src/main/java/com/baeldung/memoryleaks/equalshashcode/PersonOptimized.java new file mode 100755 index 0000000000..3af70dd1eb --- /dev/null +++ b/core-java/src/main/java/com/baeldung/memoryleaks/equalshashcode/PersonOptimized.java @@ -0,0 +1,25 @@ +package com.baeldung.memoryleaks.equalshashcode; + +public class PersonOptimized { + public String name; + + public PersonOptimized(String name) { + this.name = name; + } + + @Override + public boolean equals(Object o) { + if (o == this) return true; + if (!(o instanceof PersonOptimized)) { + return false; + } + PersonOptimized person = (PersonOptimized) o; + return person.name.equals(name); + } + + @Override + public int hashCode() { + int result = 17; + result = 31 * result + name.hashCode(); + return result; + }} diff --git a/core-java/src/main/java/com/baeldung/memoryleaks/finalize/BulkyObject.java b/core-java/src/main/java/com/baeldung/memoryleaks/finalize/BulkyObject.java new file mode 100755 index 0000000000..ce77d883f6 --- /dev/null +++ b/core-java/src/main/java/com/baeldung/memoryleaks/finalize/BulkyObject.java @@ -0,0 +1,32 @@ +package com.baeldung.memoryleaks.finalize; + +import java.nio.charset.Charset; +import java.util.Random; + +public class BulkyObject { + private String data[]; + + public BulkyObject() { + data = new String[1000000]; + + for(int i=0; i<1000000; i++) { + data[i] = getRandomString(); + } + } + + private String getRandomString() { + byte[] array = new byte[1000]; + new Random().nextBytes(array); + return new String(array, Charset.forName("UTF-8")); + } + + @Override + public void finalize() { + try { + Thread.sleep(100); + } catch (InterruptedException e) { + e.printStackTrace(); + } + System.out.println("Finalizer called"); + } +} diff --git a/core-java/src/main/java/com/baeldung/memoryleaks/finalize/BulkyObjectOptimized.java b/core-java/src/main/java/com/baeldung/memoryleaks/finalize/BulkyObjectOptimized.java new file mode 100644 index 0000000000..dc1302432e --- /dev/null +++ b/core-java/src/main/java/com/baeldung/memoryleaks/finalize/BulkyObjectOptimized.java @@ -0,0 +1,22 @@ +package com.baeldung.memoryleaks.finalize; + +import java.nio.charset.Charset; +import java.util.Random; + +public class BulkyObjectOptimized { + private String data[]; + + public BulkyObjectOptimized() { + data = new String[1000000]; + + for(int i=0; i<1000000; i++) { + data[i] = getRandomString(); + } + } + + private String getRandomString() { + byte[] array = new byte[1000]; + new Random().nextBytes(array); + return new String(array, Charset.forName("UTF-8")); + } +} diff --git a/core-java/src/main/java/com/baeldung/memoryleaks/innerclass/BulkyObject.java b/core-java/src/main/java/com/baeldung/memoryleaks/innerclass/BulkyObject.java new file mode 100755 index 0000000000..bbd5310182 --- /dev/null +++ b/core-java/src/main/java/com/baeldung/memoryleaks/innerclass/BulkyObject.java @@ -0,0 +1,22 @@ +package com.baeldung.memoryleaks.innerclass; + +import java.nio.charset.Charset; +import java.util.Random; + +public class BulkyObject { + private String data[]; + + public BulkyObject() { + data = new String[1000000]; + + for(int i=0; i<1000000; i++) { + data[i] = getRandomString(); + } + } + + private String getRandomString() { + byte[] array = new byte[1000]; + new Random().nextBytes(array); + return new String(array, Charset.forName("UTF-8")); + } +} diff --git a/core-java/src/main/java/com/baeldung/memoryleaks/innerclass/InnerClassDriver.java b/core-java/src/main/java/com/baeldung/memoryleaks/innerclass/InnerClassDriver.java new file mode 100755 index 0000000000..06f928bc4a --- /dev/null +++ b/core-java/src/main/java/com/baeldung/memoryleaks/innerclass/InnerClassDriver.java @@ -0,0 +1,17 @@ +package com.baeldung.memoryleaks.innerclass; + +public class InnerClassDriver { + public static InnerClassWrapper.SimpleInnerClass getSimpleInnerClassObj() { + return new InnerClassWrapper().new SimpleInnerClass(); + } + + public static void main2(String[] args) { + InnerClassWrapper.SimpleInnerClass simpleInnerClassObj = getSimpleInnerClassObj(); + System.out.println("Debug point"); + } + + public static void main(String[] args) { + StaticNestedClassWrapper.StaticNestedClass simpleInnerClassObj = new StaticNestedClassWrapper.StaticNestedClass(); + System.out.println("Debug point"); + } +} diff --git a/core-java/src/main/java/com/baeldung/memoryleaks/innerclass/InnerClassWrapper.java b/core-java/src/main/java/com/baeldung/memoryleaks/innerclass/InnerClassWrapper.java new file mode 100755 index 0000000000..25fecf9bb3 --- /dev/null +++ b/core-java/src/main/java/com/baeldung/memoryleaks/innerclass/InnerClassWrapper.java @@ -0,0 +1,10 @@ +package com.baeldung.memoryleaks.innerclass; + + +public class InnerClassWrapper { + private BulkyObject bulkyObject = new BulkyObject(); + + public class SimpleInnerClass { + + } +} diff --git a/core-java/src/main/java/com/baeldung/memoryleaks/innerclass/StaticNestedClassWrapper.java b/core-java/src/main/java/com/baeldung/memoryleaks/innerclass/StaticNestedClassWrapper.java new file mode 100755 index 0000000000..d1729d78a3 --- /dev/null +++ b/core-java/src/main/java/com/baeldung/memoryleaks/innerclass/StaticNestedClassWrapper.java @@ -0,0 +1,10 @@ +package com.baeldung.memoryleaks.innerclass; + + +public class StaticNestedClassWrapper { + private BulkyObject bulkyObject = new BulkyObject(); + + public static class StaticNestedClass { + + } +} diff --git a/core-java/src/main/java/com/baeldung/memoryleaks/internedstrings/InternedString.java b/core-java/src/main/java/com/baeldung/memoryleaks/internedstrings/InternedString.java new file mode 100644 index 0000000000..cbba8f849d --- /dev/null +++ b/core-java/src/main/java/com/baeldung/memoryleaks/internedstrings/InternedString.java @@ -0,0 +1,17 @@ +package com.baeldung.memoryleaks.internedstrings; + +public class InternedString { + private static final String FILEPATH = "C:\\bigstring.txt"; + + public void readString() { + String s1 = ReadStringFromFileUtil.read(FILEPATH).intern(); + String s2 = ReadStringFromFileUtil.read(FILEPATH).intern(); + + if (s1 == s2) { + System.out.println("Both the strings objects are same"); + } + else { + System.out.println("Both the strings objects are different"); + } + } +} diff --git a/core-java/src/main/java/com/baeldung/memoryleaks/internedstrings/ReadStringFromFileUtil.java b/core-java/src/main/java/com/baeldung/memoryleaks/internedstrings/ReadStringFromFileUtil.java new file mode 100644 index 0000000000..2b7d72accc --- /dev/null +++ b/core-java/src/main/java/com/baeldung/memoryleaks/internedstrings/ReadStringFromFileUtil.java @@ -0,0 +1,34 @@ +package com.baeldung.memoryleaks.internedstrings; + +import java.io.BufferedReader; +import java.io.FileReader; +import java.io.IOException; + +public class ReadStringFromFileUtil { + + public static String read(String fileName) { + BufferedReader br = null; + try { + br = new BufferedReader(new FileReader(fileName)); + StringBuilder sb = new StringBuilder(); + String line = br.readLine(); + + while (line != null) { + sb.append(line); + sb.append("\n"); + line = br.readLine(); + } + return sb.toString(); + } catch (IOException e) { + e.printStackTrace(); + } finally { + try { + br.close(); + } catch (IOException e) { + e.printStackTrace(); + } + } + return null; + } + +} diff --git a/core-java/src/main/java/com/baeldung/memoryleaks/internedstrings/StringObject.java b/core-java/src/main/java/com/baeldung/memoryleaks/internedstrings/StringObject.java new file mode 100644 index 0000000000..e48e448d18 --- /dev/null +++ b/core-java/src/main/java/com/baeldung/memoryleaks/internedstrings/StringObject.java @@ -0,0 +1,17 @@ +package com.baeldung.memoryleaks.internedstrings; + +public class StringObject { + private static final String FILEPATH = "C:\\bigstring.txt"; + + public void readString() { + String s1 = ReadStringFromFileUtil.read(FILEPATH); + String s2 = ReadStringFromFileUtil.read(FILEPATH); + + if (s1 == s2) { + System.out.println("Both the strings objects are same"); + } + else { + System.out.println("Both the strings objects are different"); + } + } +} diff --git a/core-java/src/main/java/com/baeldung/memoryleaks/staticfields/NonStaticFieldsDemo.java b/core-java/src/main/java/com/baeldung/memoryleaks/staticfields/NonStaticFieldsDemo.java new file mode 100644 index 0000000000..f2b220e76d --- /dev/null +++ b/core-java/src/main/java/com/baeldung/memoryleaks/staticfields/NonStaticFieldsDemo.java @@ -0,0 +1,21 @@ +package com.baeldung.memoryleaks.staticfields; + +import java.util.ArrayList; +import java.util.List; + +public class NonStaticFieldsDemo { + public List list = new ArrayList<>(); + + public void populateList() { + for (int i = 0; i < 10000000; i++) { + list.add(Math.random()); + } + System.out.println("Debug Point 2"); + } + + public static void main(String[] args) { + System.out.println("Debug Point 1"); + new NonStaticFieldsDemo().populateList(); + System.out.println("Debug Point 3"); + } +} diff --git a/core-java/src/main/java/com/baeldung/memoryleaks/staticfields/StaticFieldsDemo.java b/core-java/src/main/java/com/baeldung/memoryleaks/staticfields/StaticFieldsDemo.java new file mode 100644 index 0000000000..17cebc2843 --- /dev/null +++ b/core-java/src/main/java/com/baeldung/memoryleaks/staticfields/StaticFieldsDemo.java @@ -0,0 +1,21 @@ +package com.baeldung.memoryleaks.staticfields; + +import java.util.ArrayList; +import java.util.List; + +public class StaticFieldsDemo { + public static List list = new ArrayList<>(); + + public void populateList() { + for (int i = 0; i < 10000000; i++) { + list.add(Math.random()); + } + System.out.println("Debug Point 2"); + } + + public static void main(String[] args) { + System.out.println("Debug Point 1"); + new StaticFieldsDemo().populateList(); + System.out.println("Debug Point 3"); + } +} \ No newline at end of file diff --git a/core-java/src/test/java/com/baeldung/memoryleaks/equalshashcode/PersonMemoryLeakUnitTest.java b/core-java/src/test/java/com/baeldung/memoryleaks/equalshashcode/PersonMemoryLeakUnitTest.java new file mode 100644 index 0000000000..3fa1db18d2 --- /dev/null +++ b/core-java/src/test/java/com/baeldung/memoryleaks/equalshashcode/PersonMemoryLeakUnitTest.java @@ -0,0 +1,33 @@ +package com.baeldung.memoryleaks.equalshashcode; + +import static org.junit.Assert.assertTrue; + +import java.util.HashMap; +import java.util.Map; + +import org.junit.Ignore; +import org.junit.Test; + +public class PersonMemoryLeakUnitTest { + @Test + @Ignore // Test deliberately ignored as memory leak tests consume lots of resources + public void givenMap_whenEqualsAndHashCodeNotOverridden_thenMemoryLeak() { + Map map = new HashMap(); + for(int i=0; i<10000000; i++) { + map.put(new Person("jon"), 1); + } + assertTrue(map.size() > 1); + System.out.print("Debug Point - VisuaLVM"); + } + + @Test + @Ignore // Test deliberately ignored as memory leak tests consume lots of resources + public void givenMap_whenEqualsAndHashCodeOverridden_thenNoMemoryLeak() { + Map map = new HashMap(); + for(int i=0; i<10000; i++) { + map.put(new PersonOptimized("jon"), 1); + } + assertTrue(map.size() == 1); + System.out.print("Debug Point - VisuaLVM"); + } +} diff --git a/core-java/src/test/java/com/baeldung/memoryleaks/finalize/FinalizeMemoryLeakUnitTest.java b/core-java/src/test/java/com/baeldung/memoryleaks/finalize/FinalizeMemoryLeakUnitTest.java new file mode 100644 index 0000000000..b6d81a8968 --- /dev/null +++ b/core-java/src/test/java/com/baeldung/memoryleaks/finalize/FinalizeMemoryLeakUnitTest.java @@ -0,0 +1,28 @@ +package com.baeldung.memoryleaks.finalize; + +import org.junit.Ignore; +import org.junit.Test; + +public class FinalizeMemoryLeakUnitTest { + @Test + @Ignore // Test deliberately ignored as memory leak tests consume lots of resources + public void givenObjectWithFinalizer_whenCreatingAndDestroyingThisObject_thenMemoryLeak() { + BulkyObject[] stock = new BulkyObject[100000]; + + for(int i=0; i<100000; i++) { + stock[i] = new BulkyObject(); + } + System.out.print("Debug Point - VisuaLVM"); + } + + @Test + @Ignore // Test deliberately ignored as memory leak tests consume lots of resources + public void givenObjectWithoutFinalizer_whenCreatingAndDestroyingThisObject_thenNoMemoryLeak() { + BulkyObjectOptimized[] stock = new BulkyObjectOptimized[100000]; + + for(int i=0; i<100000; i++) { + stock[i] = new BulkyObjectOptimized(); + } + System.out.print("Debug Point - VisuaLVM"); + } +} diff --git a/core-java/src/test/java/com/baeldung/memoryleaks/innerclass/StaticInnerClassMemoryLeakUnitTest.java b/core-java/src/test/java/com/baeldung/memoryleaks/innerclass/StaticInnerClassMemoryLeakUnitTest.java new file mode 100644 index 0000000000..0854e4a38a --- /dev/null +++ b/core-java/src/test/java/com/baeldung/memoryleaks/innerclass/StaticInnerClassMemoryLeakUnitTest.java @@ -0,0 +1,20 @@ +package com.baeldung.memoryleaks.innerclass; + +import org.junit.Ignore; +import org.junit.Test; + +public class StaticInnerClassMemoryLeakUnitTest { + @Test + @Ignore // Test deliberately ignored as memory leak tests consume lots of resources + public void givenUsingInnerClass_whenInitializingInnerClass_thenInnerClassHoldsReferenceOfOuterObject() { + InnerClassWrapper.SimpleInnerClass simpleInnerClassObj = new InnerClassWrapper().new SimpleInnerClass(); + System.out.print("Debug Point - VisuaLVM"); + } + + @Test + @Ignore // Test deliberately ignored as memory leak tests consume lots of resources + public void givenUsingStaticNestedClass_whenInitializingInnerClass_thenStaticNestedClassDoesntReferenceOuterObject() { + StaticNestedClassWrapper.StaticNestedClass staticNestedClassObj = new StaticNestedClassWrapper.StaticNestedClass(); + System.out.print("Debug Point - VisuaLVM"); + } +} diff --git a/core-java/src/test/java/com/baeldung/memoryleaks/internedstrings/StringInternMemoryLeakUnitTest.java b/core-java/src/test/java/com/baeldung/memoryleaks/internedstrings/StringInternMemoryLeakUnitTest.java new file mode 100644 index 0000000000..6d363e0bdc --- /dev/null +++ b/core-java/src/test/java/com/baeldung/memoryleaks/internedstrings/StringInternMemoryLeakUnitTest.java @@ -0,0 +1,20 @@ +package com.baeldung.memoryleaks.internedstrings; + +import org.junit.Ignore; +import org.junit.Test; + +public class StringInternMemoryLeakUnitTest { + @Test + @Ignore // Test deliberately ignored as memory leak tests consume lots of resources + public void givenJava6OrBelow_whenInterningLargeStrings_thenPermgenIncreases() { + new InternedString().readString(); + System.out.print("Debug Point - VisuaLVM"); + } + + @Test + @Ignore // Test deliberately ignored as memory leak tests consume lots of resources + public void givenJava6OrBelow_whenNotInterningLargeStrings_thenPermgenDoesntIncrease() { + new StringObject().readString(); + System.out.print("Debug Point - VisuaLVM"); + } +} diff --git a/core-java/src/test/java/com/baeldung/memoryleaks/staticfields/NonStaticFieldsMemoryLeakUnitTest.java b/core-java/src/test/java/com/baeldung/memoryleaks/staticfields/NonStaticFieldsMemoryLeakUnitTest.java new file mode 100644 index 0000000000..e64fdb73e0 --- /dev/null +++ b/core-java/src/test/java/com/baeldung/memoryleaks/staticfields/NonStaticFieldsMemoryLeakUnitTest.java @@ -0,0 +1,26 @@ +package com.baeldung.memoryleaks.staticfields; + +import java.util.ArrayList; +import java.util.List; + +import org.junit.Ignore; +import org.junit.Test; + +public class NonStaticFieldsMemoryLeakUnitTest { + public List list = new ArrayList<>(); + + public void populateList() { + for (int i = 0; i < 10000000; i++) { + list.add(Math.random()); + } + System.out.println("Debug Point 2"); + } + + @Test + @Ignore // Test deliberately ignored as memory leak tests consume lots of resources + public void givenNonStaticLargeList_whenPopulatingList_thenListGarbageCollected() { + System.out.println("Debug Point 1"); + new NonStaticFieldsMemoryLeakUnitTest().populateList(); + System.out.println("Debug Point 3"); + } +} diff --git a/core-java/src/test/java/com/baeldung/memoryleaks/staticfields/StaticFieldsMemoryLeakUnitTest.java b/core-java/src/test/java/com/baeldung/memoryleaks/staticfields/StaticFieldsMemoryLeakUnitTest.java new file mode 100644 index 0000000000..1765f0cf0d --- /dev/null +++ b/core-java/src/test/java/com/baeldung/memoryleaks/staticfields/StaticFieldsMemoryLeakUnitTest.java @@ -0,0 +1,26 @@ +package com.baeldung.memoryleaks.staticfields; + +import java.util.ArrayList; +import java.util.List; + +import org.junit.Ignore; +import org.junit.Test; + +public class StaticFieldsMemoryLeakUnitTest { + public static List list = new ArrayList<>(); + + public void populateList() { + for (int i = 0; i < 10000000; i++) { + list.add(Math.random()); + } + System.out.println("Debug Point 2"); + } + + @Test + @Ignore // Test deliberately ignored as memory leak tests consume lots of resources + public void givenStaticLargeList_whenPopulatingList_thenListIsNotGarbageCollected() { + System.out.println("Debug Point 1"); + new StaticFieldsDemo().populateList(); + System.out.println("Debug Point 3"); + } +}